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• QUARTERLY GROUNDWATER MONITORING AND SAMPLING REVIEW 4614 W. TURNER RD. , LODI PAGE 4 Laboratory analyses indicate trace amounts of xylene in MW-3 and MW-8 However, the laboratory commented that the readings are considered to be suspect since the analyte was detected in the instrument blank. In addition, analyses indicated 200 ug/L TPH as weathered gasoline in MW-3 . Summary' Five quarters of groundwater monitoring and sampling at the Sebastiani Vineyards site is detailed in the above text MW-1 is the well closest to the site of the former underground tank, and has always shown the highest levels of contaminants . It was converted into an extraction well in October , 1992 , as part of a groundwater treatment program MW-3 continues to show intermittent reading of contaminants , including benzene (7/24/92 ) , TPHg (5/7/93) , and TPH as weathered gasoline (8/17/93) . The data suggests the contaminant plume has stabilized in the area monitored by MW-1 and MW-3 . Although trace amounts of contaminants have been detected in other wells , these have been isolated incidents followed by clean testing . There has been no indication of the plume spreading or migrating Water levels have risen the last two quarters to levels above those of 1988 , when the tank was removed. Future quarterly testing will be sensitive to the possibility of contaminants previously suspended in the soil now reaching the water . So far, the only indication of such a trend is the 200 ug/L reading of TPH as weathered gasoline in MW-3 during the most recent quarter. The next quarterly sampling will occur in November , 1993 . At that time, a complete round of sampling ( 8 wells) will be done. I can be reached at (209) 339-1311 with any questions or comments you may have related to this project . Yours truly, SEBASTIANI VINEYARDS fSTephen Manildi Attachments cc: California Regional Water Quality Control Board